Peter didn't understand the vision he had in Acts 10 to mean that all meats were now clean. God sent that vision to teach that gentiles were not to be considered unclean.
Act 10:17 Now while Peter was greatly perplexed in mind as to what the vision which he had seen might be, behold, the men who had been sent by Cornelius, having asked directions for Simon's house, appeared at the gate;
Peter couldn't understand why God in a vision would tell him that unclean animals were now clean. That was not a teaching of Jesus, or at least Peter didn't recognize it as such because Acts 10 takes place nearly 25 or 30 years after the death of Christ and:
Act 10:14 But Peter said, "By no means, Lord, for I have never eaten anything unholy and unclean."
But Peter did eventually figure out what the vision meant, and he tells us:
Act 10:28 And he said to them, "You yourselves know how unlawful it is for a man who is a Jew to associate with a foreigner or to visit him; and yet God has shown me that I should not call any man unholy or unclean.